This invention relates to a thin-film forming apparatus and a thin-film forming method used for manufacturing electronic devices.
A thin-film forming apparatus, wherein a reactive gas is introduced into a reaction chamber and the introduced reactive gas is activated by plasma and light to form a thin film, is widely used for manufacturing electronic devices.
In a thin-film forming apparatus, a substrate is loaded in a reaction chamber to which a material gas is supplied under a predetermined pressure, and the material gas is activated by applying a high-frequency electric power to grow a film of growth seeds in the material gas on the substrate.
In a thin-film forming apparatus, if a film forming method wherein a film formation rate depends on the supply quantity of the material gas is used, as shown in a curve (b) in FIG. 4, it is well known that the thickness of a film grown on a substrate is liable to vary by variation of the film formation rate.
Further, curve (b) of FIG. 4 indicates a film thickness of each substrate, in the case where a gas obtained by mixing TEOS and oxygen at a predetermined ratio is used as the material gas, and the reaction chamber is evacuated for three hours and thereafter film formation for two minutes and substrate transfer are repeated at a timing shown in FIG. 3.
The curve (b) of FIG. 4 shows that film thickness decreases (film formation rate decreases) as film formation is repeated. Specifically, it is difficult to provide substrates having constant and stable characteristics.
Therefore, if these substrates are used for an electronic device which is an end product, there are problems that operation of the electronic device is not stabilized, and that characteristics vary between devices.
The object of the present invention is to provide a thin-film forming apparatus and a thin-film forming method, which decrease variation of film formation rate and can form thin films having stable film thickness.
The present invention has been made in consideration of the above problems, which provides a thin film, comprising the steps of: supplying a material gas into a reaction chamber; and forming a thin film on a substrate with a predetermined pressure, wherein a pressure control gas having no ability to independently forming a film is supplied into the reaction chamber in a thin-film non-formation time period before forming the thin film, thereby controlling the pressure in the reaction chamber to be substantially equal to the predetermined pressure.
Further, the thin film, comprising the steps of: supplying a material gas into a reaction chamber having a heating mechanism on which a substrate is set and an electrode disposed to face the heating mechanism; and forming a thin film on the substrate, wherein the heating mechanism is in a heating state in a thin-film non-formation time period before forming the thin film, and a pressure control gas having no ability to independently forming a film is supplied to the reaction chamber in order to prevent an increase of a temperature of the electrode.
Further, the thin-film forming apparatus comprising: a reaction chamber having a heating mechanism on which a substrate is set and an electrode disposed to face the heating mechanism; a material gas introducing mechanism for supplying a material gas for film formation into the reaction chamber; and a pressure control gas introducing mechanism for supplying into the reaction chamber a pressure control gas for pressure control in the reaction chamber in a thin-film non-formation period.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.